Fans



Nov. 22, 1966 P. BAVERSTOCK FANS Filed Oct. 1, 1964 k r T0 fws y v a MB P- m P q Mark Hqenf United States Patent 3,286,914 FANS Peter Baverstock, Lee-on-Solent, England, assignor to Brightside Heating and Engineering Company Limited,

Sheflield, England Filed Oct. 1, 1964, Ser. No. 400,843

Claims priority, application Great Britain, Oct. 29, 1963,

42,510/63 1 Claim. (Cl. 230-432 This invention relates to fans of the kind known as centrifugal fans in which air or other gas is drawn into the center of the fan and expelled radially or tangentially, the fans including a scroll fixed in the fan casing and disposed about a rotor on which the fan blades are mounted, this scroll being located eccentrically or possibly concentrically of the rotor axis and defining a guide for the air or gas and terminating at the ouflet or outlets of the fan.

The object of the present invention is to provide an improved construction adapted for the reduction of noise when the fan is working.

According to the present invention a fan of the kind referred to is provided with a scroll which is perforated over substantially its entire length and is backed by sound absorbent material over the whole perforated area, the scroll being of sinuous, corrugated or other non-planar form in the direction parallel to the rotor axis.

The scroll may be made of light gauge expanded sheet metal and may be formed by profiling rollers into a configuration designed to minimize turbulent air flow in directions other than that induced by the fan and hence to avoid vibration and resonance in the fan casing,

The sound absorbent material may be mineral wool, cork, glass fibres or any combination of these materials or of any other sound deadening material.

The invention is more particularly described with reference to the accompanying drawing, wherein the sole figure is a part sectional perspective and somewhat diagrammatic view of a centrifugal fan in accordance with the invention.

The fan shown in the drawing comprises a rotor having a plurality of peripheral blades 11 and located in a stationary and fixed casing generally indicated at 12. Casing 12 includes a scroll 13 which extends about the 3,286,914 Patented Nov. 22, 1966 ice rotor from one edge of the tangential fan outlet to the other. The scroll is eccentric to the rotor axis, and is of zig-zag or saw-tooth lateral section: the angle 14 of the individual parts of the zig-zag is at least 45 to the axis of the rotor and may be greater. The individual zig-zags are preferably at least /2" in height, i.e. the distance radially of the rotor axis between a plane containing the inner set of apices of the scroll and the outer set of apices of the scroll is greater than /2".

The scroll is made of perforated metal and is backed by sound-absorbing mineral wool 15.

I claim:

In a centrifugal fan, the combination of a casing including a pair of side walls at least one of which isprovided with an air inlet opening and also including a marginal wall provided with an air outlet, a rotor mounted in said casing, a scroll in the casing comprising an elongated and longitudinally curved plate surrounding said rotor in spaced relation from said marginal wall with the ends of the plate terminating at said air outlet, said scroll plate being foraminous over its entire area and having a saw-tooth cross-section extending transversely across the full width of the casing between said side walls, said saw-tooth cross-section of the scroll plate defining a set of spaced parallel V-shaped ridges and intermediate V-shaped valleys extending longitudinally of the plate in a circumferential direction around said rotor and in planes parallel to the plane of rotation of the rotor, and packing of sound-absorbing material provided in the space between said scroll plate and the marginal wall of the casing, said packing also filling the V-shaped valleys existing between the ridges of the plate facing said marginal wall.

References Cited by the Examiner UNITED STATES PATENTS 1,233,115 7/1917 Osborne 103-103 2,855,142 10/ 1958 White 230-133 3,174,682 3/1965 Wilfert et a1 103-114 X FOREIGN PATENTS 926,088 5/1963 Great Britain.

ROBERT M. WALKER, Primary Examiner. 

